The switching speed of power semiconductors is limited by parasitic inductances and capacitances of the electronics package carrying the power semiconductors. One solution for circuit boards to reduce the parasitics is to embed the power semiconductors and their connections within the substrate of the circuit board. This permits to create short, metallic interconnections, which may minimise distortions due to parasitics.
An embedded technology also may provide the opportunity to embed EMI shield(s) with a high level of isolation from inductively and capacitively coupled noise into the circuit board, which may eliminate the need for an additional surface-mounted shield. With higher power and higher switching frequencies, for example achievable with wide bandgap semiconductors, the parasitic inductance problems may become worse.
For example, WO 2012/072212 A2 shows a power electronics package, with several electrically conducting layers, which are laminated together with a prepreg material, in which also a semiconductor chip is embedded.
However, packaging the power semiconductor chips very dense together may be challenging in the view of cooling the power semiconductors and a thermal management of the electronics package. Placing chips closer together may reduce the parasitic problem but the semiconductor chips as heat sources are more proximate to one another which may result in poor thermal spreading and hot spots. While the global temperature may not be excessive, the local hot spot temperature at a semiconductor chip may prohibit an efficient operation and may reduce the lifetime of the semiconductor chip.
It is known to cool an electronics package from one side with a cooling body. However, this only allows a one-sided cooling and may prevent chip stacking within the electronics package. There are also other solutions, how electronics packages may be cooled. For example, U.S. 2012/0228779 A1 relates to a chip comprising vertical fluid vias.
Further, a printed circuit board provided with a heat circulating medium is known from U.S. 2008/0286531 A1.